What makes breasts grow are your hormones (not just estrogen) which means you can grow your breasts naturally by eating certain types of foods which increases hormone levels in your body. But for this to be successful, don't just raise your hormone levels. Raise the certain hormone at a certain time of your menstrual cycle. Let me explain:
When you go through your menstrual cycle, your body raises certain hormones throughout the cycle. So when your body raises estrogen, you need to eat foods that increase estrogen levels in your body and when your body raises progesterone levels, then eat foods that increase progesterone in your body.
Here is a video that explains it better than I can: Click Here
It can take at least 6 weeks to show results by doing it this way. It's like going to the gym, changing your body takes time as your body need to process all the changes.